How to find subdomain take over

First what is subdomain takeover ?
A service named ‘assets’ on your website which located at assets.mysite.com hosted at third party like bitbucket or heroku at this url mysiteasset2015.heroku.com , and this service is not used on heroku , you just decided to use it and it expired or you did not claim it before but you added a dns entry pointing to heroku , so an attacker can claim it , then when you visit assets.mysite.com you are redirected to attacker site on heroku .

Scenario
1- Facebook starts new service like shop
2- Facebook points a subdomain to the Shop-service, eg shop.facebook.com
3- Mark stops the project and facebook forgets to remove the subdomain redirection pointing to the shop system.
4-Attacker signs up for the Service and claims the domain as theirs.
5- Attacker now can post a defacement or put an HTML Form and asks users to login (Perform phishing attack)

Solution
Check your DNS-configuration for subdomains pointing to services not in use.

Note From detectify
Hackers can claim subdomains with the help of external services. This attack is practically non-traceable, and affects at least 17 large service providers and multiple domains are affected. Find out if you are one of them by using our quick tool, or go through your DNS-entries and remove all which are active and unused OR pointing to External Services which you do not use anymore.

How to detect??
So here we go for detecting !
Detection of this issue is so simple , you just to need to get a list of subdomains and visit them
if you find a page error not found like this

3 COMMENTS

Look , we did not cover the exploitation because it is not the not the same on all cases , you are not injecting a payload , it is a matter of registration , suppose the following

1-you found something point to this subdomain uber.egyserv.com
2-the vulnerable subdomain is owned by uber , but they did not claim it at egyserv.com
3- Search google for ‘register domain at egyserv.com
4- go and register ,upload something like html page
5- now you exploit it